With the action set to begin Saturday, keep an eye on these swimmers at the London Aquatics Centre:
Michael Phelps, Ryan Lochte. Phelps has won 16 Olympic medals in his career; Lochte has won six. They will compete against one another in the individual medleys then join forces on the relays. Lochte won five gold medals at the 2011 world championships and set a world record in the 200 IM.
Missy Franklin. The fresh face of the U.S. swim team won five medals, including three golds, at the 2011 worlds at the age of 16. For that she was named FINA's swimmer of the year and targeted for Olympic success. She could win anywhere from four to seven medals (100 and 200 back, 100 and 200 free plus three relays).
Gemma Spofforth. The 24-year-old Brit is s medal contender in the 100 back. Last year, at 23, she contemplated suicide after a series of deaths, including her mom's to cancer. She has since become a crisis counselor and has trained at the University of Florida.
Stephanie Rice. The 23-year-old Australian won three gold medals at the 2008 Olympics and became the queen of Queensland swimming. She has been bothered by a shoulder injury the past year but qualified for her second Olympics.
James Magnussen. The Missile. He could be the world's fastest swimmer and Australia's next swim star al a Grant Hackett and Ian Thorpe. His chief challengers will be Brazil's Cesar Cielo and France's Alain Bernard and Yanick Angel.
Federica Pellegrini. She is the first female Olympic champion in the history of Italian swimming (200 free). She is also the only Italian swimmer to have set world records in more than one event yet is equally known for out-of-the-pool antics and glamourizing.
Kristy Coventry. The 28-year-old Zimbabwe native won gold in the 200 back in both 2004 and 2008. She won four Olympic medals in Beijing and was declared her country's "national treasure." She swam and studied at Auburn University.
Sun Yang. China's towering freestyler is the swim phenom who has bridged the gap between short distances (200) to long (1,500). He broke the 1,500 world record at last year's worlds and is poised for greatness in London.
Kosuke Kitajima. The Japanese dynamo could become one of the first swimmers to win three consecutive gold medals, and he could do it in two events (100, 200 breast). Phelps may also do the same in the 100, 200 butterfly.
Tae-Hwan Park. Hailed as Marine Boy, the South Korean freestyler won gold and silver medals in Beijing. He also won gold in the 400 free at the 2011 worlds and has been working with Australian coach Michael Bohl, who thinks Park can break the 400 world record.